Photosensors such as charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS) and the like have been widely applied in mobile phones, safety monitoring systems, or industrial tester. As a result, there is increasing demand for testing the photosensors. Because most photosensors comprises a large number of cells of array, the spatial uniformity of a photosensor depends on whether each cell could have the same response to the light beams with the same intensity or not. Whether the responses to the light beams with different wavelengths for each cell are the same or not would determine whether a photosensor could achieve white balance or not. And the speeds of the responses to incident light beams for each cell would determine the response speed of a photosensor. That is to say, these are the optical properties which determine the quality of a photosensor.
In order to obtain the spatial uniformity and white balance data of a photosensor, as illustrated in FIGS. 1 and 2, the traditional tester 1 for testing photosensors includes a high intensity discharge lamp 10, an optical processing device 11 and a light detecting device. The high intensity discharge lamp 10 is used to provide light beams with different wavelengths to the optical processing device 11, after homogenizing the light via the color wheel 110 in the optical processing device 11 and the subsequent optical lens module, projecting the homogeneous light after this treatment onto the loading seat 12. The homogeneous light passes through the aperture 121 in the upper cover 120, illuminating a photosensor under test 13, such as a CMOS chip. Each cell in the photosensor under test 13 senses the incident intensities and then the corresponding sense signals by its conversion would be outputted to a control device (not shown) via a plurality of leads 122 electrically connected to the photosensor, thus obtaining the testing results. The operations such as classification (shipping inspection), reduction of the pixels and gray scales of defectives within the acceptable range (serve as sub-quality products), and the like are performed according to the testing results.
However, the traditional tester 1 for testing photosensors needs to be equipped with the above high intensity discharge lamp 10, optical processing device 11, loading seat 12 and the like. In particular, the optical processing device occupies a large space, leading to a relatively high cost. Furthermore, halogen bulbs are often used as the high intensity discharge lamp 10 so that it would become a serious defect in those tests, which require stable-wavelength light sources, due to the drifts and unstable wavelength values of each wavelength component in the above halogen bulb light sources. In addition, frequent replacement of the bulbs also results in relatively higher cost due to their great consumption.